Depth-of-Field Rendering with Multiview Synthesis SigGraph Asia 2009 Sungkil Lee, Elmar Eisemann, and Hans-Peter Seidel Sunyeong Kim Nov. 2 nd. 2010

2 GOAL ● GPU-based real time rendering method ● High-quality Depth-of-Field effect ● Similar in quality to multiview accumulation methods.

3 BASIC KNOWLEDGE ● Depth of Field (DOF) ● Circle of Confusion (COC) ● Thin-lens Model

4 DOF & COC

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6 THIN-LENS MODEL

7 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

8 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

9 Scene Decomposition ● Single render pass scene decomposition ● The depth intervals δ are uniformly with respect to the signed COC radius C(d)

10 Scene Decomposition Video

11 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

12 Layer Creation ● On current hardware ● Multiple render targets do not allow independent z-buffer ● Texture Tiling ● “Layered rendering” ● Pixel depth, corresponding layer L ● Approximation – not split triangles at the layer boundary

13 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

14 DOF Blur ● Using Layered Representation

15 DOF Blur ● Ray Traversal ● Each layer represents a height field. ● Iterative approximation inspired by the Method of False Position.

16 DOF Blur ● Handling Off-Screen Pixels ● Decomposition from the lens center ● Discard all rays that leave the frustum ● Early Layer Culling ● Large blank image areas ● Skipping intersection test ● If a minimum depth value is greater than the depth bounds of the layer, No intersection & test skip!

17 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

18 Cone Tracing ● Need sufficient lens samples ● Rays are continuous ● Single ray only result in one precise point ● Rays to Cone! ● correspond to an infinite ray set centered around the original ray ● lead to higher quality

19 Approximate Cone Tracing ● Cone Tracing ● correspond to an infinite ray set centered around the original ray ● lead to higher quality ● Using Mipmap with alpha channel and average color

20 OVERVIEW ● Scene Decomposition ● Layer Creation ● DOF Blur ● Approximate Cone Tracing ● Jittered Lens Sampling

21 Jittered Lens Sampling ● Insufficient sampling leads to visible aliasing artifact

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23 RESULT

24 RESULT

25 DISCUSSION ● Pros ● Faster to multiview accumulation method ● Highly scalable with the number of views and layers ● Cons ● The lack of anti-aliasing ● Trade-off : performance ↔ accuracy This method is good to produce high-quality DOF blur in real time.

26 CONCLUSION ● Trade-off : performance ↔ accuracy This method is good to produce high-quality DOF blur in real time.

27 Thank you! Question or Comment?